Portraying Earth

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Portraying Earth
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Objectives

• To know basic characteristics of the maps as a
  tool for studying geography
• To understand the ways a landscape can be
  portrayed through map projection, photos and
  Remote sensing

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Outline

• 1. The nature of maps
• 2. The role of Globes
• 3. Map projections
• 4. Automated Cartography
• 5. Isolines
• 6. New technology GIS, GPS and Remote Sensing
• 7. Role of Geographer
• 8. Focus studies

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1. Nature of Maps

• Map as a 2D model
• Distance, distribution, pattern, direction, size
  shape in horizontal spatial relationship
• Scale ratio of map and actual on the ground
• RF Representative factor
• Scale types
• Fractional,
• verbal
• Graphic uses a line marked off in graduated
  distances
• No map perfectly accurate. Smaller the area being
  mapped more accurate it can be.
• Small scale has small representative fraction,
  gives limited details, shows larger area and
  Large scale has larger RF

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1. Nature of Maps
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Examples of Map Scales
Figure 2-3
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Map essentials

• Map essentials
• A map has title scale
• 3Dto2L and 1 P you tell
• Title
• Scale
• Date
• Direction
• Data Source
• Legend
• Location
• Projection System

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2. Role of the Globes

• Maintain correct relationship of meridian
  parallels, poles, comparative sizes, continents
  and oceans
• Can show comparative distances, sizes and
  accurate directions
• Can represent the spatial relation of features on
  the earths surface without distortion

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3. Map Projections

• Transform a rounded 3D surface to 2D map
• Fundamental problem is to minimize distortion
• Make a grid to capture geometry of globe
• Have most distortion in less important part of
  map
• Use blank spaces in oceans to decrease distortion
  of continents. Central meridians pass through
  center of land masses and serve as baseline for
  mapping continents
• Uses mathematical computation
• The dilemma is equivalence versus conformity
• Equivalence equal area, Conformity angular
  relationship
• Large scale maps or small scale maps ?
• Art of compromise Robinson Projection

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Conic Projection
Figure 2-6
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Plane Projection
Figure 2-7
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Cylindrical Projection
Figure 2-8
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Pseudo-Cylindrical Projection
Pseudocylindrical projections resemble
cylindrical projections, with straight and
parallel latitude lines and equally spaced
meridians, but the meridians are curved. Central
meridian and equator cross at right angle.
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Interrupted Projection
Figure 2-9
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4. Automated Cartography

• Computer technology provides several great
  benefits to cartography
• Improved speed and data-handling ability
• Reduced time involved in map production
• Can examine alternative map layouts

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5. Isolines

• Isoline joins points of equal value to
  represent a spatial distribution of a phenomena.
  ( also called isarithm, isogram, isopleth, and
  isometric line)
• Contour line equal elevation
• Isobar Equal pressure
• Isogonic lineequal magnetic declination
• Isohyet Equal Precipitation
• Isotherm Equal temperature
• The lines are closed, no end, rarely touch or
  cross
• Interval numeric difference between two lines
• Proximity depends on the gradient

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Isolines Elevation
Figure 2-12
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IsolinesAverage Annual Precipitation
Figure 2-13a
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6. New Technology

• GIS
• GPS
• Remote Sensing

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What is it?
The Geographic Positioning System is a satellite
based system for determining accurate positions
on or near the surface of the earth.
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GPS

• Global positioning system, satellite-based system
  for determining accurate positions on or near
  earth surface
• 24 High altitude satellites provide
  identification and position information
• Receivers get the information
• Based on signals at least four satellites provide
  the position info based on distance computations

• Military units can accurately pinpoint
• Also used in earthquake prediction, ocean floor
  mapping, volcano monitoring and mapping projects

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Global Positioning System (GPS)
Figures 2-16
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GIS

• Geographic information Systems/Science
• Capture
• Store
• Retrieve
• Analysis and
• Display of spatial data

• Consists of
• Hardware
• Software
• Data
• People and institutions
• Can use library of information
• Research tool for geographic analysis and enquiry
  
• Links maps and tabular data and characterization
• Uses different maps to produce purposeful maps
• Used in many disciples
• High market

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Geographic Information Systems (GIS)
Figure 2-29
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Remote sensing

• Different kinds of remote sensing techniques
• Aerial photos
• Orthophotos
• Color and color infrared Sensing (color refers
  to visible-light region of spectrum)
• Thermal infrared sensing (Middle or far infrared)
• Microwave remote sensing (100 micrometer to 1m)
• Radar (radio wave lengths longer than 1m) and
  sonar sensing (sound ranging)
• Multispectral remote sensing
• MSS (30 m pieces of info covering 110 mile x 110
  miles)
• TM
• SPOT

• Study of an object or surface from a distance by
  using various instruments
• Sophisticated tool to study earth and geography
• Data input to GIS

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Aerial Photographs

Photograph taken from an elevated platform
Figure 2-18
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7. Role of Geographer

• Works as an interpreter
• Analyst
• Integration of filed study, descriptions and maps
• Use best tools to fit the purpose

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8. Focus Studies

• Map essentials
• A map has title scale
• 3Dto2L and 1 P you tell
• Mercator 400 years ago for straight line
  navigation, High altitude land masses appear
  bigger, Conformal so Distortion in mid and high
  latitude, meridians are used as parallel straight
  lines
• USGS topographic Maps Relief shape, slope,
  elevation
• Topographic maps show meridians and parallels no
  political boundaries, now prepared through remote
  sensing and computer rectification